A Bar-Based Nomogram for Predicting Septic Shock in Patients with Acute Pancreatitis Complicated by Sepsis: Development and External Validation.

BACKGROUND: Septic shock is a common and life-threatening complication in patients with acute pancreatitis (AP) complicated by sepsis, yet rapid and accurate tools for early risk prediction remain limited in clinical practice. This study aimed to develop and externally validate a nomogram incorporating the blood urea nitrogen-to-albumin ratio (BAR) to predict the risk of progression to septic shock in this high-risk population.

METHODS: In this retrospective multicohort study, a total of 541 patients with AP complicated by sepsis were identified from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database and randomly divided into a training set (n = 379) and an internal validation set (n = 162) at a 7:3 ratio. An independent cohort of 295 patients from the Second Hospital of Hebei Medical University was used for external validation. Candidate variables collected within the first 24 hours of intensive care unit admission were screened using least absolute shrinkage and selection operator regression. A multivariable logistic regression model was constructed and visualized as a nomogram. Model performance was assessed using discrimination, calibration, and decision curve analysis.

RESULTS: Nine variables were selected to construct the nomogram, with BAR emerging as a key predictor. The model demonstrated good discriminatory performance, with areas under the receiver operating characteristic curve of 0.777 in the training cohort, 0.707 in the internal validation cohort, and 0.832 in the external validation cohort. Calibration curves showed good agreement between predicted and observed risks, and decision curve analysis indicated favorable clinical utility across a wide range of threshold probabilities. Net reclassification improvement analysis in the external validation cohort demonstrated that the BAR-based model significantly improved risk classification compared with the model including blood urea nitrogen alone (NRI = 0.247, 95% confidence intervals 0.008-0.486, P = 0.042).

CONCLUSIONS: We developed and externally validated a BAR-based nomogram for early and individualized prediction of septic shock in patients with AP complicated by sepsis. This clinically interpretable tool may facilitate early risk stratification and support timely clinical decision-making in the intensive care setting.